The Hidden Twin: A Case of Missed Heterotopic Pregnancy Revealed by Rising Beta-hCG Post-Ectopic Removal

Ectopic pregnancy (EP) refers to the implantation of a fertilized ovum outside the uterine cavity, most commonly in the fallopian tube. One key clinical marker is beta human chorionic gonadotropin (β-hCG), which typically declines following surgical removal of the ectopic tissue. Persistent or rising β-hCG post-removal often suggests incomplete removal, persistent ectopic tissue, or rarely gestational trophoblastic disease. However, a more elusive diagnosis is heterotopic pregnancy (HP), defined as the simultaneous occurrence of both intrauterine and extrauterine pregnancies. We present the case of a woman who underwent a salpingectomy for a ruptured EP diagnosed at 6 weeks gestation. Four weeks later, her β-hCG levels remained elevated. A transvaginal ultrasound revealed a viable intrauterine pregnancy (IUP) at 10 weeks’ gestation, confirming the diagnosis of HP. This case underscores the critical importance of comprehensive follow-up evaluation when β-hCG levels remain elevated after EP management. A combination of clinical assessment, serial β-hCG monitoring, point-of-care ultrasound, and formal transvaginal imaging must be employed to exclude the presence of HP and optimize patient outcomes.